Typical prior art sheet metal hole cutters comprise a circular base, a peripheral wall formed on one side of the base and extending axially therefrom, and a plurality of cutting teeth machined in the outer edge of the peripheral wall. The base, peripheral wall and cutting teeth are machined from a piece of steel to form a hole cutter of unitary construction. Exemplary sheet metal hole cutters of this type are sold by Miyanaga Co., Ltd. of Hyogo, Japan under the designation “Holesaw 278”, and by Hougen Manufacturing, Inc. of Swartz Creek, Mich., USA, under the designation “14,000-Series Holcutters”. One of the drawbacks associated with these types of prior art hole cutters is that they are relatively expensive to manufacture. For example, machining each hole cutter out of a piece of metal can be a relatively time consuming and expensive process.
In contrast to prior art sheet metal hole cutters, some prior art hole saws are manufactured by forming the saw teeth in an elongated metal band, and then welding the metal band in a circular configuration onto a rigid cap plate. Exemplary hole cutters of this type are sold by the Assignee of the present invention, American Saw & Manufacturing Co., Inc., under its LENOX® trademark. These prior art hole saws are not well suited for use as sheet metal hole cutters. For example, the radial depth of the band typically is significantly greater than necessary for cutting sheet metal. As a result, if such hole saws are used to cut sheet metal, they can be less accurate and have greater total indication run out (“TIR”) than otherwise desired. Further, such hole saws are designed to cut holes through relatively thick materials, such as wood, and therefore do not have a stop or like feature to prevent the saw from over-feeding through the work piece. Rather, such hole saws purposefully define a smooth external periphery in order to allow the hole saw to pass through the work piece. Yet another drawback associated with the use of such hole saws for cutting sheet metal is that the tooth forms do not provide a sufficiently clean or burr-free hole in the work piece, and/or do not provide sufficient clearance between the cutting teeth and the work piece to facilitate smooth and accurate cutting.
Accordingly, it is an object of the present invention to provide an improved sheet metal hole cutter that overcomes one or more of the above-described drawbacks and/or disadvantages of the prior art.